The applicant is the owner of the Spanish Patent application number 9800419 in which a disposable formwork for columns is disclosed together with the process for obtaining the same; the formwork is structured from a body or tubular core made of a plurality of expanded polystyrene pieces, fixed to each other by means of adhesive through their joining edges and coated inside by a sheet of plastic material which constitutes a watertight barrier and which is fixed to the core by means of an adhesive layer, while on the outside, the whole formwork is completed by a support in the form of a mesh consisting of a fiberglass mesh having an initial form of a band, and which is rolled up helicoidally on said tubular core, and fixed to the same by means of adhesive, such that said mesh provides appropriate mechanical rigidity to the whole.
As mentioned above, said patent application discloses also the process for obtaining the same formwork, according to which said plastic sheet is placed on a retractable mould which form and dimensions match those of the column to be obtained, said plastic sheet being closed over itself configuring a tubular body, by means of a longitudinal seal; said plastic laminar tube is then coated with an external layer of adhesive; on the other hand, the expanded polystyrene pieces or plates, constituting the body or tubular core of the formwork, have been already made and a layer of adhesive is also applied to both their internal side and their joining edges, and they are subsequently mounted in the mould, with the plastic sheet being interposed in between, said expanded polystyrene pieces being attached thereto while they are fixed to each other, in order to configure said tubular core; then, the external mesh is mounted either by applying a layer of adhesive on the tubular body or thanks to the self-adhesive nature of said mesh, which is rolled up helicoidally from a reel, either by means of the rotation of the mould together with a longitudinal movement of the reel or by means of a planetary movement of the reel around the mould, with a parallel axial movement of one element with respect to the other.
The Certificate of Addition having application Pat. No. 9,802,487 discloses some improvements introduced in said application Pat. No. 9,800,419, consisting in the replacement of the internal plastic coating by rigid plates, which form and dimensions coincide with the walls of the column to be obtained; said plates, made of plasticised wood on their internal side or of rigid plastic, are fixed to each other to configure a tubular body with the help of adhesives tapes appropriately fixed to their internal side in correspondence with the joining edges between the plates, so as to configure an inner tubular body having a completely smooth and sealed surface, on which body the above mentioned pieces made of expanded polystyrene are placed, said pieces constituting the intermediate, rigid tubular body, used to stabilize said plates and on which, in turn, said fiberglass mesh is placed externally, rolled up helicoidally and fixed by means of adhesive, in order to provide the formwork as a whole of the appropriate mechanical resistance. It is also necessary, in this case, in order to place the fiberglass mesh reinforcement to submit the rest of the formwork to a rotational movement or to provide the mesh delivering reel with a planetary movement, combined in any case with an axial and relative movement between the reel and the mould wearing the formwork.